The invention relates to a vibratory packing plank for a road finisher, having a vibration unit, which comprises a vibration element exhibiting a large-area base plate and coupled to a vibration drive, and a guide plate positioned obliquely towards the base plate.
Road finishers conventionally comprise a packing plank, especially having a basic plank body which is divided for the adjustment of a roof profile and which can usually be widened to either side by an extendible plank and, where appropriate, additionally by plank parts which can be manually pieced together. The packing plank can also however be designed as a so-called "rigid" construction, i.e. the different packing widths are achieved by the attachment of plank extensions to both sides of the basic plank. The packing plank is pivotally attached to the road finisher by two traction arms, so that it is able to float on the material to be packed. As a tamping vibration plank, it can comprise a combination of a tamping and a vibrating device, the tampers and vibration elements of which are disposed one behind the other in the direction of travel.
From EP-B-0 115 567, a packing plank of this type is known, which is provided with at least two tampers driven by an eccentric shaft, which tampers are disposed one behind the in the direction of travel and to which there is adjoined a vibration element comprising a base plate. Since the vibration drive exerts, via the large-area base plate, only a small specific surface pressure upon the packing material, the compacting effect of the vibration is restricted relative to the tamping compaction. Especially in the production of very thin packing layers, the compacting effect of the rear tamper in the direction of travel, which compacting effect is too high for this packing instance, can result in the packing plank being raised in the rear region, thereby impairing its compacting effects.
Furthermore, packing planks are known in which at least one vibration strip provided with a run-in slope is located behind the base plate of the packing plank in the direction of travel. The compacting effect of the vibration strips is restricted, in particular on an uneven foundation such as, for example, where lane grooves are built upon, since no fresh packing material is able to be supplied to the vibration strip. The result of this is an irregular compaction.
The foregoing illustrates limitations known to exist in present vibratory packing planks. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.